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To take one example of evaluation research, Taylor et al (2003) compared the efficacy of exposure therapy, EMDR and relaxation training on 60 participants with long term PTSD. They found all three techniques were effective when comparing pre- and post- intervention scores, although for some symptoms (i.e., reexperiencing and avoidance symptoms) exposure therapy was more effective.
You might also find the literature review in the article useful.

The NLP technique known as the "Fast Phobia Cure" works by dissociaton. The practitioner would have the client imagine themselves in a large movie theatre, watching a movie of themselves having the phobic experience. Watching it in fast motion, forward, then backward, etc. This is the first dissociation -- They are watching themselves on that screen.

Next, the client is asked to go into the projection room, and look down at themselves in the theatre, watching the movie. Same thing, watching it in fast motion, forward then backward. This is the second dissociation (watching themselves in the seat watching the movie)

Finally, the client is asked to visualize the movie theatre, watching it from a distance, watching themselves in the projection booth watching themsevles in the seat, watching themselves on the screen. This is the third dissociation.

This is all happening subconsciously, and disssociates themselves from the reaction to the phobic event.

Source: I am a hypnotherapist, and NLP practitioner, and I use this technique in my practice. It